This study investigates the relationship between financial development and economic growth for 6 ASEAN countries including Thailand, Singapore, Philippines, Malaysia, Indonesia and Vietnam over 1988 - 2012. Using three indicators to measure the financial development level and controlling for appropriate macroeconomic factors, we find that both stock market capitalization and deposit and lending rates margin have a positive effect (but only statistically significant for stock market capitalization) on the economic growth, while the credit to private sector has a significantly negative impact on the economic growth. These findings are robust after controlling for the financial and economic crises in 1997 and 2008. We attribute the negative effect of credit to private sector on economic growth to the low efficiency of the banking system in the Southeast Asian countries.